The present invention relates to an image forming apparatus of the type exposing the surface of an image carrier with a laser beam in accordance with image data to thereby form a latent image thereon, developing the latent image to thereby produce a corresponding toner image, transferring the toner image to a recording medium, and then fixing the toner image on the recording medium. More specifically, the present invention is concerned with an image forming apparatus capable of stabilizing the linear velocity of the image carrier susceptible to the linear velocity of the recording medium during the transfer of the toner image.
In an image forming apparatus of the type described, when a toner image is transferred from an image carrier, e.g., photoconductive element to a paper sheet, the rotation of the image carrier and the conveyance of the paper sheet are control led such that the linear velocity of the image carrier coincides with the linear velocity of the paper sheet, as measured at an image transfer position. Any difference between the two linear velocities causes the image carrier to rub the toner image carried on the paper sheet at the time of image transfer, thereby blurring the toner image or varying the length thereof in the subscanning direction. So long as the linear velocities are coincident, the toner image can be transferred from the image carrier to the paper sheet without the magnification thereof being varied. However, even if the mean linear velocity of the image carrier and that of the paper sheet are coincident, the linear velocities each are apt to fluctuate. Particularly, sharp variation in linear velocity gives rise to problems that will be described specifically with reference to the accompanying drawings.
Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 6-149077, 8-146789, 8-160782, 10-308858, and 11-65396.
It is therefore an object of the present invention to provide an image forming apparatus capable of preventing the speed of an image carrier from sharply varying.
An image forming apparatus of the present invention includes an image carrier for carrying a toner image thereon while being driven to rotate. A conveyor conveys a recording medium, to which the toner image is to be transferred from the image carrier, to an image transfer position. An image carrier controller controls the linear velocity of the image carrier in rotation. A conveyance controller controls the linear velocity of the recording medium being conveyed by the conveyor. A main controller controls the image carrier controller and conveyance controller such that the mean linear velocity of the image carrier and that of the recording medium are different from each other.